AND POLYHYDRIC ALCOHOLS 159 



attached to the terminal carbon atom in the sugar chain, i.e. 

 in the position marked No. 6 in the following formula : 



(6) (5) (4) (3) (2) (1) 



CH 2 (OCH 3 ) . CH(OH) . CH . CH(OH) . CH(OH) . CH(OH) 







The substance may therefore be termed 6-monomethylglucose. 



The method of preparation adopted was to condense 

 glucose with acetone under conditions which result in the 

 formation of glucosediacetone (Fischer, Ber., 28, 1165, 2496). 

 The reaction is troublesome and uncertain in its results, on 

 account of the necessity to convert glucose in the first instance 

 into a dimethyl acetal, and, moreover, as the acetone residues 

 are exceedingly liable to undergo hydrolysis, precautions have 

 to be taken throughout the preparation to avoid the access of 

 either moisture or traces of acid. We have, however, been 

 able to improve on Fischer's process, and have succeeded in 

 increasing the yield of product considerably. The methyla- 

 tion of the substance was conducted with the precautions 

 found advisable in the case of the corresponding fructose 

 derivative, and the same proportion of the alkylating mixture 

 was used. The product was purified by fractional distillation 

 (b.p. 139-140/12mm.) and the yield was almost quantitative. 



Analysis showed the compound to be pure monomethyl 

 glucosediacetone, the properties and solubilities of which 

 resembled those of other methylated sugar derivatives of a 

 glucosidic nature. 



The compound showed [a]f-32-2 in alcohol and -31-8 

 in acetone solution, the concentration in each case being 

 5 per cent. 



The removal of the acetone residues took place with extreme 

 ease on heating an aqueous-alcoholic solution, containing 

 0'4 per cent, of hydrogen chloride, for 100 minutes in boiling 

 water. The course of the reaction was followed polarimentric- 

 ally, and the results showed that both acetone groups were 



